1. Field of the Invention
This invention relates generally to portable viewing apparatus useful in providing its user with enhanced images and, more particularly, to apparatus that can provide a stereoscopic or three-dimensional image when a first kind of program material is being viewed and that can provide a wide-angle image when a second kind of program material is being viewed.
2. Description of the Related Art
Stereoscopic viewing apparatus are used by a viewer to view two related two-dimensional images displayed on a suitable screen and thereby realize a three-dimensional effect. The related images depict the same scene, but as viewed from the perspectives of two locations spaced horizontally a distance approximating the distance between the centers of a typical viewer's eyes. The apparatus provides a three-dimensional effect by causing the viewer's left and right eyes to view the left and right displayed images, respectively. The perceived three-dimensional image has the two-dimensional proportions of the individual two-dimensional images being displayed.
One common type of stereoscopic viewing apparatus is used to view a motion picture of two related images that are projected onto a movie screen such that they overlap. In one version, the light defining the two images is polarized 90 degrees with respect to each other, and the movie screen is adapted to maintain the polarization. To separate the overlapping polarized images, the stereoscopic viewing apparatus includes appropriate polarized filters placed before the viewer's eyes. This polarization technique cannot be used with conventional television receivers, because, unlike movie screens, conventional television screens cannot display the requisite polarized images.
In another version of this common type of stereoscopic viewing apparatus, the two projected images are displayed in different colors, and the viewing apparatus separates the overlapping images using appropriately-colored filters placed before the viewer's eyes. A significant drawback to this version is that it frequently cannot display images in their true colors regardless of the type of filters used.
Another example of a prior type of stereoscopic viewing apparatus views a motion picture of two related images that are displayed on a movie screen side-by-side, rather than overlapping. The device transmits the left and right images to the left and right eyes, respectively, without the use of filters. The images could conceivably be adapted for side-by-side display on the screen of a conventional television receiver. However, for the two related images and thus the three-dimensional image to have the same two-dimensional proportions (i.e., aspect ratio) as the conventional television image, the related images cannot occupy all the available vertical dimension of the screen. Thus, this type of apparatus would be unable to utilize the television screen's entire vertical resolution capability.
Many motion pictures are filmed for display on a special wide screen. When such motion pictures are being broadcast for display on conventional television receivers or are being shown on a standard motion picture screen, the images ordinarily are cropped to eliminate portions of their left and right sides. Alternatively, the images must be boxed with black stripes along their top and bottom edges, which reduces the image's effective height. In either case, the viewing experience is diminished in quality.
It will be appreciated from the foregoing that there is a definite need for a portable stereoscopic viewing apparatus for use in viewing on a conventional television screen two side-by-side related images, using the entire vertical resolution capability of the television screen, yet providing a three-dimensional image having the two-dimensional proportions of the conventional television image. It also will be appreciated that there is a need for a viewing apparatus for use in viewing the entirety of wide-screen motion picture images on standard television screens or standard motion picture screens, using the entire screen. The present invention fulfills these needs.